Stereopsis is the process in visual perception that allows perception of depth from two or more slightly different projections of a view onto the retinas of two eyes. Stereopsis was first described by Charles Wheatstone in 1838 (“Contributions to the Physiology of Vision.—Part the First. On some remarkable, and hitherto unobserved, Phenomena of Binocular Vision”, Philosophical Transactions of the Royal Society of London, Vol. 128, pp. 371-394, 1838), which led to many attempts to achieve stereoscopic display by providing different images to the left and right eyes of a viewer using, for example, eye-glasses incorporating filters of a different color (e.g., red and cyan) or polarization for each eye.
Advances in computer graphics have created a recent resurgence in interest in multi-dimensional display for motion pictures and television. Multi-dimensional displays are typically referred to as 3D (three-dimensions, referring to the three spatial dimensions) or 4D (four-dimensions, referring to the three spatial dimensions and the added dimension of time).
There are two types of stereoscopic displays: those that require special eyeglasses and those that do not, the latter being referred to as autostereoscopic display systems. One conventional method of achieving autostereoscopy involves the use of lenticular lens arrays (see, for example, U.S. Pat. No. 1,128,979, “Stereoscopic Picture,” W. Hess, Feb. 6, 1916). Another conventional approach is the use of barrier grids, also known as “parallax barriers”, as described by Frederick E. Ives, “A novel stereogram,” Journal of the Franklin Institute 153: 51-52, 1902). Some of commercial image display systems and image content that use conventional stereoscopic technologies exhibit deficiencies in at least one of viewer experience, system complexity, and system cost.
Visual deficiencies arise in conventional stereoscopic technologies, in part, because human perception of 3D does not depend on the parallax embodied in stereoscopy alone, but is also affected by the focal distance of the eye, obscuration of an object in the background by a nearer object, relative angular motion of objects at different distances, and motion as detected by the inner ear and saccadic motion. In fact, motion sickness and eyestrain are reported to result from viewing displays that are based on stereoscopy alone (“3D TV and Movies: Exploring the Hangover Effect”, J. Hecht, Optics & Photonics News, February 2011, p, 20-27). That is, human depth perception is not solely based on binocular vision but rather is formed from multiple cues. These cues include, but are not limited to, relative object size, dynamically changing object size, motion parallax, apparent relative motion of different objects, accommodation by each eye, occlusion of one object by another, shadows, and the like. The cue inputs are integrated by a viewer's brain to generate the experience of depth perception.